As we know, netlink sockets are private resource of net namespace, they can communicate with each other only when they in the same net namespace. this works well until we try to add namespace support for other subsystems which use netlink. Don't like ipv4 and route table.., it is not suited to make these subsytems belong to net namespace, Such as audit and crypto subsystems,they are more suitable to user namespace. So we must have the ability to make the netlink sockets in same user namespace can communicate with each other. This patch adds a new function pointer "compare" for netlink_table, we can decide if the netlink sockets can communicate with each other through this netlink_table self-defined compare function. The behavior isn't changed if we don't provide the compare function for netlink_table. Signed-off-by: Gao feng <gaofeng(a)cn.fujitsu.com&gt; --- Actually I already send a patchset to add namespace support for audit subsystem [1]. this patch is a part of the patchset. I think it's better to send this patch out separately, since some people may have comments on this one. I need to know what's the idea of network guy. [1] http://lwn.net/Articles/549546/ include/linux/netlink.h | 1 + net/netlink/af_netlink.c | 33 +++++++++++++++++++++++++-------- net/netlink/af_netlink.h | 1 + 3 files changed, 27 insertions(+), 8 deletions(-) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index 6358da5..f78b430 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -46,6 +46,7 @@ struct netlink_kernel_cfg { void (*input)(struct sk_buff *skb); struct mutex *cb_mutex; void (*bind)(int group); + bool (*compare)(struct net *net, struct sock *sk); }; extern struct sock *__netlink_kernel_create(struct net *net, int unit, diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 12ac6b4..e399877 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -854,16 +854,23 @@ netlink_unlock_table(void) wake_up(&nl_table_wait); } +static bool netlink_compare(struct net *net, struct sock *sk) +{ + return net_eq(sock_net(sk), net); +} + static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid) { - struct nl_portid_hash *hash = &nl_table[protocol].hash; + struct netlink_table *table = &nl_table[protocol]; + struct nl_portid_hash *hash = &table->hash; struct hlist_head *head; struct sock *sk; read_lock(&nl_table_lock); head = nl_portid_hashfn(hash, portid); sk_for_each(sk, head) { - if (net_eq(sock_net(sk), net) && (nlk_sk(sk)->portid == portid)) { + if (table->compare(net, sk) && + (nlk_sk(sk)->portid == portid)) { sock_hold(sk); goto found; } @@ -976,7 +983,8 @@ netlink_update_listeners(struct sock *sk) static int netlink_insert(struct sock *sk, struct net *net, u32 portid) { - struct nl_portid_hash *hash = &nl_table[sk->sk_protocol].hash; + struct netlink_table *table = &nl_table[sk->sk_protocol]; + struct nl_portid_hash *hash = &table->hash; struct hlist_head *head; int err = -EADDRINUSE; struct sock *osk; @@ -986,7 +994,8 @@ static int netlink_insert(struct sock *sk, struct net *net, u32 portid) head = nl_portid_hashfn(hash, portid); len = 0; sk_for_each(osk, head) { - if (net_eq(sock_net(osk), net) && (nlk_sk(osk)->portid == portid)) + if (table->compare(net, osk) && + (nlk_sk(osk)->portid == portid)) break; len++; } @@ -1161,6 +1170,7 @@ static int netlink_release(struct socket *sock) kfree_rcu(old, rcu); nl_table[sk->sk_protocol].module = NULL; nl_table[sk->sk_protocol].bind = NULL; + nl_table[sk->sk_protocol].compare = NULL; nl_table[sk->sk_protocol].flags = 0; nl_table[sk->sk_protocol].registered = 0; } @@ -1183,7 +1193,8 @@ static int netlink_autobind(struct socket *sock) { struct sock *sk = sock->sk; struct net *net = sock_net(sk); - struct nl_portid_hash *hash = &nl_table[sk->sk_protocol].hash; + struct netlink_table *table = &nl_table[sk->sk_protocol]; + struct nl_portid_hash *hash = &table->hash; struct hlist_head *head; struct sock *osk; s32 portid = task_tgid_vnr(current); @@ -1195,7 +1206,7 @@ retry: netlink_table_grab(); head = nl_portid_hashfn(hash, portid); sk_for_each(osk, head) { - if (!net_eq(sock_net(osk), net)) + if (!table->compare(net, osk)) continue; if (nlk_sk(osk)->portid == portid) { /* Bind collision, search negative portid values. */ @@ -2282,9 +2293,12 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module, rcu_assign_pointer(nl_table[unit].listeners, listeners); nl_table[unit].cb_mutex = cb_mutex; nl_table[unit].module = module; + nl_table[unit].compare = netlink_compare; if (cfg) { nl_table[unit].bind = cfg->bind; nl_table[unit].flags = cfg->flags; + if (cfg->compare) + nl_table[unit].compare = cfg->compare; } nl_table[unit].registered = 1; } else { @@ -2707,6 +2721,7 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) { struct sock *s; struct nl_seq_iter *iter; + struct net *net; int i, j; ++*pos; @@ -2714,11 +2729,12 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) if (v == SEQ_START_TOKEN) return netlink_seq_socket_idx(seq, 0); + net = seq_file_net(seq); iter = seq->private; s = v; do { s = sk_next(s); - } while (s && sock_net(s) != seq_file_net(seq)); + } while (s && !nl_table[s->sk_protocol].compare(net, s)); if (s) return s; @@ -2730,7 +2746,8 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) for (; j <= hash->mask; j++) { s = sk_head(&hash->table[j]); - while (s && sock_net(s) != seq_file_net(seq)) + + while (s && !nl_table[s->sk_protocol].compare(net, s)) s = sk_next(s); if (s) { iter->link = i; diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h index ed85222..eaa88d1 100644 --- a/net/netlink/af_netlink.h +++ b/net/netlink/af_netlink.h @@ -73,6 +73,7 @@ struct netlink_table { struct mutex *cb_mutex; struct module *module; void (*bind)(int group); + bool (*compare)(struct net *net, struct sock *sock); int registered; }; -- 1.8.1.4